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Muir Woods National Monument Exploration

You may not think of salmon when visiting the redwoods in Muir Woods, but it's home to a population of Coho Salmon.

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Difficulty: Moderate

Length: 6 miles

Duration: 1-3 hours

Overview :
You may not think of salmon when visiting the redwoods in Muir Woods, but it’s home to a population of Coho Salmon. Redwood forests... more » provide ideal salmon habitat, providing woody debris to protect young salmon in the creeks and keeping them shaded and cool. But the Coho in Muir Wood’s Redwood Creek are endangered, and local biologists and volunteers are working to protect the salmon and restore their habitat.

Points of Interest

Female Coho look for areas like these in Redwood Creek to lay their eggs. The loose gravel and steady water flow protect the eggs and ensure a supply of oxygen.

After spawning, female coho use their bodies to dig a nest, or redd, in gravel at the bottom of Redwood Creek. The eggs will remain buried in the creek bottom until they hatch.

A... More female can lay hundreds of eggs in her nest.

Credit: Richard James.

Fish Biologist Michael Reichmuth explains the life cycle of Redwood Creek's Coho. The number of returning salmon have been dropping in recent years, causing concern about the health of the population.Less

2. Wild Cucumber

Wild Cucumber (Marah fabaceus) is also known as Man Root, due to the large tuberous root underground. The root is toxic and was reportedly used by Native American groups to stun fish, making them much easier to catch.

You can recognize Wild Cucumber (Marah fabaceus) by its curly vines or spiky green seed pods in the summer.

Milk Maids ... More(Cardamine californica) are common wildlfowers across California, typically blooming from January through May. Other fun colloquial names include California Toothwort and Bitter cress.Less

3. Oregon Forestsnail

Saw this lovely mollusk climbing a mossy trunk , shell alomst 2" in diameter. Best guess is the Oregon Forestsnail (Allogona townsendiana). Any other ideas?

4. Tree Break

When a redwood topples, it often takes down a number of other trees, thanks to its massive height and weight. If it falls into the creek, it's good news for salmon, since it creates new habitat.

The Muir Woods redwoods are old-growth trees. They escaped much of the logging common to the California coast thanks to the steep terrain surrounding the... More valley.

You'll see both Tanoaks (Lithocarpus densiflorus) and Coast Live Oaks (Quercus agrifolia) in Muir Woods, but many will look like this. Sudden Oak Death is wide-spread in Marin County and is caused by the pathogen Phytophthora ramorum. Infected trees often develop cankers that ooze dark liquid. The pathogen prevents the tree from sending nutrients and energy between the leaves and roots, eventually killing the tree. The pathogen spores are spread by other trees, water and even humans.Less

5. Redwood Sorrel

This may look like clover, but Redwood Sorrel (Oxalis oregano) isn't part of the clover family. It thrives in the low light of the redwood understory.

The Big Leaf Rhododendron (Rhododendron macrophyllum) can be found in local nurseries, but in Muir Woods, they're rare. There are only three populations left in Marin County. This plant was... More sprouted from seeds collected by the Golden Gate National Parks Conservancy, who are working to preserve the genetic variation of this local population. These rhododendrons benefit from fire cycles and are among the first plants to reappear after a fire. While it's thought that fires historically came through Muir Woods every 20-30 years, the last fire was in the 1840's.

A Trillium flower (Trillium ovatum).Less

6. It's a Burl

Lumpy burls are usually found at the base of redwood trees, but this tree's burl is high overhead. Redwoods use burls as one method of reproduction. They can simply sprout new growth from the burl if the main tree is stressed or damaged.

7. Witch’s Butter (Tremella mesenterica)

Witch's Butter (Tremella mesenterica) is a jelly fungus that is actually a parasite. It feeds on another type of fungus that lives on dead wood.

The flame-like ripples of the False Turkey-tail, or Stereum hirsutum, are lovely, but too tough to be edible. Common in Bay Area woodlands, Stereum hirsutum is easy to mistake for Trametes versicolor,... More the "actual" Turkey Tail fungus.

Brown Witches Butter (Tremella foliacea) like many fungi is found growing on the wood of dead trees. Here it appears to be parasitizing False Turkey-tail, or Stereum hirsutum.Less

8. Fetid Adder’s Tongue

In order to spread its seed far and wide, the Fetid Adder's Tongue, or Slinkpod (Scoliopus bigelovii) grows its seed pods on long, thin stalks. As they grow larger, the stalks bend away from the plant and touch the ground. Each has a packet of nutrients that attracts ants and other insects, which help carry the seeds even further.

The Fetid... More Adder's Tongue blooms early - you'll see these flowers in December or January. They have a slightly foul smell which attracts pollinators like gnats, instead of bees.Less

9. Yellow Waxy Cap

The Yellow Waxy Cap (Hygrocybe flavescens) is a bright yellow mushroom often found in redwood forests.

Likely these are Oyster Mushrooms (Pleurotus ostreatus), sought after by mushroom hunters for their culinary uses. Anyone able to confirm?

10. Albino Redwood

This is a redwood tree, but its needles are white. They're lacking chlorophyll, the green substance that helps plants do photosynthesis. Because it can't make food on its own, this tree acts like a parasite, tapping into the roots of another redwood.

There are only a handful of known albino redwoods in California. They can only survive by living... More on other trees.Less

11. Shady Pools

Pools like these, created by toppled trees, are crucial for Coho Salmon, who like cold, clean water. Returning salmon rest in pools like these as they head up the creek to spawn. Juvenile salmon rely on creek pools to protect them. Today, the Park Service is in the process of adding wood pack to Redwood Creek, since it was once their policy to... More remove it.

These young Coho were caught in a fish survey. After hatching, they're known as "fry." They spend 16-18 months living in the creek, eating bug larvae.

Image: Chris Friedel.

Native sculpin like these prey on juvenile salmon in Redwood Creek. Young salmon also have to worry about non-native crayfish.

Image. Richard James.

Sometimes when looking around the forest floor, things look back.Less

12. Convergent Ladybugs

Throughout the winter in the Bay Area, you may see large groups of ladybugs clustering together. These Convergent Lady Beetles (Hippodamia convergens) come together for their winter hibernation and huddle together to conserve warmth and energy.

13. Spawning Salmon

In December and January, Coho return to Redwood Creek, completing their three year life cycle. They rely on winter rains to raise the level of the creek, which breeches a sandbar that often forms at the outlet to the ocean. The salmon return to the creeks they were born in to mate and lay eggs.

Image. Richard James.

After spawning, the Coho... More die. If you look closely, you can see small circle punched out of the salmon's skin, which were taken for a biological survey when this salmon was found.

Credit: Richard James.

Each year, biologists from the Point Reyes National Seashore survey Redwood Creek for Coho Salmon and Steelhead Trout. They work to find out how many salmon are returning each year, to help estimate the health of the population. Coho are listed as an endangered species. In the 1940s, California's population was estimated at 200,000 to 500,000. In just 50 years, that population has declined about 90%.

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